Multi-RAT mobile communication devices are capable of communicating via different RAT interfaces. For example, most 3rd Generation (3G) mobile communication devices are capable of communicating based on the Global System for Mobile Communication (GSM) and the Wideband Code Division Multiple Access (WCDMA) standards. In such multi-RAT mobile communication devices, the different RAT interfaces are typically integrated in one network access module which is implemented as a chip or chip set.
However, the design effort for integrating different RAT interfaces in one network access module is high, in particular since the different RAT interfaces share common resources and have to be adjusted to each other. Furthermore, integrating different RAT interfaces in one network access module lacks flexibility, since for adding an additional RAT interface or replacing one RAT interface with another RAT interface, the chip or chip set has to be designed anew.
Moreover, future RAT interfaces (e.g., according to the Long Term Evolution (LTE) standard) are becoming more and more complex so that it is technically difficult or may even become technically impossible to integrate a future RAT interface with another RAT interface in one network access module.
In order to avoid the design effort and the disadvantages of integrating different RAT interfaces in one network access module, it could be thought about implementing each RAT interface in a separate network access module in the mobile communication device, as is known, for example, from US 2007/0173283 A1. For such an implementation, the need to synchronize the separate network access modules arises.